In order to provide enhanced indoor cellular telecommunications network coverage at a customer's home or office, it is known (see FIG. 1) to provide the customer with a femto-cell base station 10, also known as Home Node B (HNB) or simply as a femto-cell. The Home Node B 10 typically has an xDSL router and modem, thereby facilitating the provision of different native cellular telecommunications services (both voice and data services) by using an existing customer xDSL line 11 to connect the Home Node B 10 to the core network 30 of the cellular telecommunications network 40. The Home Node B 10 and xDSL router and modem device may be separate devices or a single hybrid device (as in FIG. 1). The femto-cell supports both 3G and LTE technologies just through a change in the software configuration.
A further development of the router device combines the xDSL router and modem device with a cellular telecommunications modem (e.g. an HSPA/LTE modem or USB dongle); the cellular telecommunications modem is configured to provide a wireless connection with the cellular telecommunications network 40 in case the xDSL connection fails, or also at the time of first using the device (if the xDSL line has not been provisioned and is not working yet).
Problems arise when both the Home Node B 10 and the cellular telecommunications modem use radio frequencies associated with the same cellular telecommunications network. In particular, problems may occur with the available carriers: the radio access technology and the frequency allocated to the HNB 10 (for indoor communications) can be the same as the “macro layer” technology and frequency used by the cellular telecommunications modem. Therefore, if there is a failure in the DSL line (or there is no operational xDSL line for some other reason) and the HSPA/LTE backup starts working, there may be interference thereby preventing the femto-cell base station or Home Node B and the macro network connection from working simultaneously.
Currently, such interference (which may occur whenever the DSL link is not available for some reason and the cellular telecommunications modem has to be activated to provide backup connection), may only be avoided by automatically disabling the Home Node B.